1. Field of the Invention
This invention relates to a low power loss Mn-Zn ferrite suitable for use in power applications.
2. Related Art Statement
So-called Mn-Zn ferrites are widely used as a core material of coils or transformers in various communication machinery and equipment, power supplies and the like. Recently, with the spreading of office automation equipment, they are used as a transformer material of switched mode power supply operated at a high frequency region of about 100 kHz.
For these applications, many characteristics such as high saturation magnetic flux density, high permeability and low power loss are required of Mn-Zn ferrites. In the transformer for the switched mode power supply aiming at the invention, a low power loss characteristic under a high magnetic field is most important.
For this end, it has hitherto been attempted to improve these properties by adding various trace components to Mn-Zn ferrite.
For instance, Japanese Patent laid open No. 58-15037 discloses the addition of Nb.sub.2 O.sub.5 and also Japanese patent laid open No. 60-132301 discloses the addition of Nb.sub.2 O.sub.5, CaO, SiO.sub.2, V.sub.2 O.sub.5, ZrO.sub.2, Al.sub.2 O.sub.3, SnO.sub.2, CuO, CoO and the like, whereby it is attempted to improve the power loss at 100 kHz which is a standard operational frequency at the present, and as a result a power loss at 100 kHz and 200 mT of about 300-350 mW/cm.sup.3 has been attained at the present.